The present invention relates to a fireplace assembly, and more particularly to masonry fireplaces.
Masonry fireplaces are well known and have been used for years. Such fireplaces are often preferred over metal wood stoves or metal fireplaces for their aesthetic qualities. However, traditional masonry fireplaces have suffered from several drawbacks. Principal among these drawbacks is that masonry fireplaces often provide inefficient and incomplete combustion, resulting in high levels of air pollution, especially in the form of particulates. This drawback has led some municipalities to ban masonry fireplaces. Yet another drawback of traditional masonry fireplaces is that they often fail to provide adequate ventilation, resulting in smoke exiting the fireplace not through the chimney, but instead "spilling" smoke through the front opening of the firebox.
Another problem with the construction of traditional masonry fireplaces has been that, in general, most masons are unfamiliar with efficient and aerodynamically effective fireplace designs. It has been known for some time that particular fireplace designs, such as the Rumford fireplace design, can provide for more efficient combustion. Unfortunately, the Rumford design requires particular geometries, which include a curved lintel and specific firewall geometry from the bottom of the firebox to the smoke chamber. In addition, the geometry of the smoke chamber, damper, and throat are critical to efficient Rumford fireplace operation. However, even for masons who are familiar with efficient fireplace designs, these particular designs are difficult for most masons to create using only mortar and brick because of the complex non-rectangular geometries that are necessary to achieve these designs.
Some attempts have been made to provide masons with forms to guide construction of functional and efficient masonry fireplaces, but these forms have not been well received. Masons have typically resisted the incorporation of metal forms into masonry fireplaces, mainly because they are accustomed to using the tools and materials of masonry construction, and because they are unaware of the limitations of the strength of masonry. More fundamentally, the expansion of metal within a fireplace may cause the surrounding masonry to crack because of the different degrees and rates of heat expansion between masonry and metal.
Another solution to guide construction of fireplaces has been to provide preformed masonry blocks that when assembled form a fireplace. However, such materials are heavy and expensive to ship and transport compared to the great volumes of materials still available locally.
One such attempt to provide a "kit" is supplied by Superior Clay of Ohio and is made almost exclusively out of extruded clay tiles in various shapes. Although this kit does not provide forms for firebox construction, it does have a single-size chimney breast tile laid on its side and strung on a simple steel angle to form an opening. This design has several drawbacks. Extruded clay tiles are appropriate in compression, as in chimney flues, but not in suspension. Over time the tiles may crack and break down. In addition, the mason must make a difficult cut into the surrounding masonry casing to fit the lintel into the right position. The kits also use very heavy clay tiles to form a variety of smoke chambers--some of which are asymmetrical and result in poor performance. The kit also uses a metal damper placed at the throat and the whole system forms a very shallow "traditional" style Rumford fireplace with interior hearths less than 16" deep. This system requires consumers to develop new and unfamiliar firing techniques such as "teepee" firing. Most operators, however, install gratings and suffer with its lack of performance, such as dirty-burning and smoke-spilling operations.
Accordingly, what is therefore needed is a fireplace assembly that allows construction of an efficient wood burning masonry fireplace, that provides for good fuel combustion with little resulting pollution, that allows masons to construct such fireplaces quickly and easily primarily with material on hand, that provides forms for the construction of difficult and precise geometries, that does not result in cracking of the masonry due to different expansion rates of the constituent materials of the fireplace assembly, that uses light-weight durable materials for the forming of geometries, and that allows operators to use traditional wood-burning methods.